This invention is in the field of implantable medical devices. More particularly, the invention is in the field of implantable devices for the detection and interruption of hyperkinetic atrial arrhythmia.
Hyperkinetic atrial arrhythmia includes a large number of generally benign disorders characterised by an increase in the frequency of atrial contraction, possibly accompanied by an increase in frequency of ventricular contraction. These increases can lead to fibrillation and flutter in which the movement of the atrium is chaotic and does not correspond to that of the ventricle.
Clinical electrocardiograms may suggest the following risks for the patient: atrial tachycardia (from 140 to 220 bpm) caused by heart disease which can result in a net reduction in the cardiac output due to reduced atrial and ventricular filling in combination with hypotension and lipothymia; atrio-ventricular junctional tachycardia with feedback of the P wave and a reduction in cardiac output; multiform supraventricular tachycardia from different atrial pacemakers functioning separately, with extreme variability of cardiac frequency; atrial flutter, in which the frequency of atrial contraction is more than 200 bpm, with a variable ventricular response depending on the conduction ratio (2:1, 3:1 etc.); and atrial fibrillation, comprising a chaotic movement of the atria which become distended and do not empty properly.
Among these atrial tachyarrhythmias, flutter and fibrillation are without doubt the most disabling. In particular, atrial fibrillation (hereafter xe2x80x9cAFxe2x80x9d) is an arrhythmia which can cause numerous problems.
For example, from the haemodynamic point of view, AF results in an absence of atrial systole which, in a normally functioning heart, increases ventricular filling by increasing both the velocity and the volume of blood flow. Its absence therefore reduces cardiac output. AF also leads to a pooling of the blood in the atrium, which favors the formation of thromboembolism. This condition is life-threatening to the patient. The irregularity of the ventricular response to the chaotic electrical activity in AF may also lead to unrestrained ventricular tachyarrhythmia, which is even more dangerous than atrial tachyarrhythmia.
The treatment of AF (and in certain cases, of atrial flutter also) consists of correcting the sinus rhythm by cardioversion. Cardioversion may be achieved using pharmacological or electrical intervention. In the latter case, a suitable anticoagulation procedure is necessary in combination with an anaesthetic or sedation being administered prior to administration of the electric shock. Pharmacological cardioversion also requires anticoagulation, but not anaesthesia, and gives rise to a longer therapeutic effect. Anticoagulation usually is not necessary if cardioversion is performed in the first 48 hours after the onset of arrhythmia.
Despite the foregoing, a need exists for a method and apparatus capable of detecting AF at its onset and interrupting it before it reaches an advanced stage.
The invention relates to an implantable device adapted for the detection and interruption of hyperkinetic atrial arrhythmia. More particularly, the invention relates to a device comprising a catheter positioned in the heart which is connected to a system for detecting AF and intervening during the early stages of AF using a drug, electrical stimulation or both. The catheter includes a first lumen capable of perfusing a drug, and optionally at least one additional lumen for inflating and deflating one or more optional balloons which, during the infusion, isolate portions of the vascularture, thereby creating conditions which allow the drug to reach the coronary arteries and the vein of Marshall. The catheter is operably connected to a housing which includes a reservoir for the drug, a system for inflating and deflating the vessel closure balloons, if they are provided, a system for infusing a bolus of drug, a sensing system for detecting atrial fibrillation in electrical or electromechanical communication with sensors, a system for the electrostimulation of the heart in arrhythmic emergencies, a two-way telemetry system for setting the infusion, sensing, and simulation parameters, and a valve port for filling the necessary drug reservoir from outside the body. The system may also include external telemetric instrumentation for programming the implanted device.